The oldest and most important of the Commentaries on the Tipiṭaka, brought, according to tradition, to Sri Lanka by Mahinda, who translated it into Singhalese (Cv.xxxvii.228 f). It thus came to be called the Sīhala-aṭṭhakathā. Besides exegetical material on the Pāḷi Canon, it contained also historical materials on which were later based the Pāḷi Chronicles, the Mahāvaṃsa and the Dīpavaṃsa. For a description see Geiger’s Dīpavaṃsa and Mahāvaṃsa, pp.44, 63, etc.
The Mahā-aṭṭhakathā was the chief source from which Buddhaghosa drew the material for his Commentaries and is often referred to in his works, particularly in the Samantapāsādikā, e.g., Sp.i.2; ii.494; 265; iii.537, 616, 617, 627, 701, 716, 718, 726; iv. 744, 776, 783, 817, 863, 914, 923; DhSA.157; DA.i.180, etc.
The Mahā-aṭṭhakathā was in the charge of the monks of the Mahāvihāra at Anurādhapura. It was superseded by the Commentaries of Buddhaghosa, Dhammapāla and others, and is not now extant. It is often referred to merely as the Aṭṭhakathā. e.g., VibhA.56, 155, 200, etc.